The present invention relates to a sheet paper attracting system for use in a sheet paper feeding system of a copying machine, a facsimile system, a printing machine, and the like.
Various types of sheet paper feeding systems have been developed for supplying a paper sheet from a storing section where a plurality of sheets are stacked. One type of sheet paper feeding system employs a sheet feed roller for feeding a paper sheet through the use of the friction caused by the rotating sheet feed roller. This type of sheet paper feeding system may damage the surface of the paper sheet. Furthermore, an accurate feeding operation is not ensured when the sheet paper has a low friction factor, or when the surface construction of the sheet feed roller becomes deteriorated due to long time usage.
Another type of the sheet paper feeding system employs an air pump for attracting a paper sheet. More specifically, a sheet paper attracting unit is connected to a suction air casing which includes a vacuum chamber therein. The sheet paper attracting unit faces the uppermost paper sheet stored in the storing section. In the conventional system, the sheet paper attracting unit is tightly fixed to the suction air casing and, therefore, an accurate attracting operation is not ensured when the paper sheet has an uneven surface, or when the relationship between the locations of the sheet paper attracting unit and the sheet paper storing section is not in exactly adjustment.
Moreover, in the above-mentioned conventional system, there is this possibility that more than one sheet of paper will be simultaneously supplied. Furthermore, since the attracting suction force is fixed in the conventional system, an accurate feeding is not ensured when the sheet thickness varies.
Accordingly, an object of the present invention is to provide a sheet paper attracting system which ensures an accurate paper sheet feeding operation.
Another object of the present invention is to provide a mechanism which allows an adjusting movement of a sheet paper attracting unit with respect to a suction air casing.
Still another object of the present invention is to provide a sheet paper attracting system which prevents the piled or multiple feeding of paper sheets even when the thickness of the paper sheet varies.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, the sheet paper attracting unit is connected to the suction air casing via a flexible duct so that the sheet paper attracting unit is movable with respect to the suction air casing.
In a preferred form, an attracting suction force control circuit is provided for varying the suction force in accordance with the thickness of a paper sheet. Furthermore, the sheet paper attracting unit is constructed to rotate by a predetermined angle while the center of a paper sheet is depressed by a depression roller in order to prevent the piled feeding of paper sheets.